The third Generation Partnership Project (3GPP) Long Term Evolution (LTE) represents a major advance in cellular technology and is the next step forward in cellular 3G services as a natural evolution of Global System for Mobile Communications (GSM) and Universal Mobile Telecommunications System (UMTS). The LTE provides for an uplink speed of up to 50 megabits per second (Mbps) and a downlink speed of up to 100 Mbps and brings many technical benefits to cellular networks. The LTE is designed to meet carrier needs for high-speed data and media transport as well as high-capacity voice support well into this decade. Bandwidth is scalable from 1.25 MHz to 20 MHz. This suits the needs of different network operators that have different bandwidth allocations, and also allows operators to provide different services based on spectrum. The LTE is also expected to improve spectral efficiency in 3G networks, allowing carriers to provide more data and voice services over a given bandwidth. The LTE encompasses high-speed data, multimedia unicast and multimedia broadcast services.
Physical layer (PHY) of the LTE standard is a highly efficient means of conveying both data and control information between an enhanced base station (eNodeB) and mobile user equipment (UE). The LTE PHY employs advanced technologies that are new to cellular applications. These include Orthogonal Frequency Division Multiplexing (OFDM) and Multiple Input Multiple Output (MIMO) data transmission. In addition, the LTE PHY uses Orthogonal Frequency Division Multiple Access (OFDMA) on the downlink (DL) and Single Carrier-Frequency Division Multiple Access (SC-FDMA) on the uplink (UL). OFDMA allows data to be directed to or from multiple users on a subcarrier-by-subcarrier basis for a specified number of symbol periods.
The LTE-Advanced is an evolving mobile communication standard for providing fourth generation (4G) services. Being defined as 3G technology, the LTE does not meet the requirements for 4G also called International Mobile Telecommunications-Advanced (IMT-Advanced) as defined by the International Telecommunication Union such as peak data rates up to 1 Gbit/s. Besides the peak data rate, the LTE-Advanced also targets faster switching between power states and improved performance at the cell edge.